These words, found in the Nicene-Constantinopolitan Creed, simply and yet boldly declare Orthodox teaching on baptism. The baptismal experience is often considered the fundamental Christian experience.

The word baptize derives from baptizo, the transliterated form of the Greek word βάπτειν or baptivzw. In a historical context, it means "to dip, plunge, or immerse" something entirely, e.g. into water. Although commonly associated with Christian baptism, the word is known to have been used in other contexts. For instance, a 2nd century author named Nicander wrote down a pickle recipe which illustrates the common use of the word. He first says that the pickle should be dipped (bapto) into boiling water, followed by a complete submersion (baptizo) in a vinegar solution. The word was also used to explain the process of submerging cloth into a colored dye. The Christian ritual of water baptism traces back to Saint John the Forerunner, who the Bible says baptized many, including Jesus. Certain forms of baptism were practiced in the Old Testament. Additionally, baptism was practiced in some pagan religions as a sign of death and rebirth.

Baptism as a Sacrament

In contrast to a common Protestant viewpoint, baptism is more than just a symbolic act of burial and resurrection, but an actual supernatural transformation. Baptism is believed to impart cleansing (remission) of sins and union with Christ in his death, burial and resurrection (see Romans 6:3-5; Colossians 2:12, 3:1-4).

Full immersion is a hallmark of an Orthodox baptism.

Baptism is performed by the three-fold immersion of a person in the name of the Holy Trinity. That is, a person is immersed "in the name of the Father, and of the Son, and of the Holy Spirit," once for each person of the Holy Trinity. The practice of baptism by the pouring or sprinkling of water, instead of full immersion, is not taught or practiced in the Orthodox Church as in some Roman Catholic and Protestant churches. Baptism is immediately followed by Chrismation and Holy Communion at the next Divine Liturgy, regardless of age.

Catechumen

Adults are baptized after they have completed their time as a catechumen.

Infant Baptism

The Orthodox also practice infant baptism on the basis of various texts (e.g. Matthew 19:14) which are interpreted to condone full Church membership for children. This is generally based on a confession of faith for a child by his or her godparents. The Orthodox Church does not practice infant baptism in order to cleanse the taint of original sin, because this doctrine is not taught in the Orthodox Church.

Validity of a baptism

Because the Sacrament of Baptism has actual spiritual and salvific effects, certain criteria must be complied with for it to be valid (i.e., to actually have those effects). Baptism in water is assumed. Violation of some rules regarding baptism render the baptism illicit (i.e., a violation of the church's laws, and a sin for those who willingly and knowingly participate in it), and yet still valid. For example, if a priest introduces some unauthorized variation in the ceremony, the baptism is still valid so long as certain key criteria are still met, even though the priest has violated the church's law and thus sinned, and so have the other participants if they know the priest's behaviour is illict.

In normal circumstances, a licit baptism must be performed by a priest or a deacon. However, in cases of a genuine emergency, anyone may perform the baptism.

One of the criteria for validity is that the correct form of words be used. Orthodox use the form "Let this servant of Christ be baptized..." or "This person is baptized by my hands..." Catholics use the form "I baptize you..." However, both churches recognize the other's form as valid. The Catholic Church teaches that the use of the verb "baptize" is essential.

It is also considered essential that the Trinitarian formula is used. Baptisms from non-Trinitarian churches, such as Oneness Pentecostal, are generally not considered valid. There was an ancient controversy over baptism using the formula that Oneness Pentecostals use, with some ancient authorities holding it to be valid. However, this was motivated by the apparent use of that formula at some places in scripture, not by anti-Trinitarian considerations (which might well invalidate the baptism even if that formula is valid). The most significant part, some theologians have argued, is not so much the Trinitarian wording, as the Trinitarian intention, and the recognition that the baptism involves all three Persons.

Some theologians have also argued that sprinkling on a part of the body other than the head in an emergency would also be valid.

A person, once baptized, cannot be baptized again. There was an ancient practice in some areas of rebaptizing those who had returned to the church from heresy, but that practice has been universally rejected.

Baptism by other denominations

The various jurisdictions of the Orthodox Church generally accept baptism performed by other denominations as valid, subject to certain conditions. It is only possible to be baptized once, thus people with valid baptisms from other denominations may not be baptized again on conversion. Instead, for these converts the sacrament of chrismation is performed. However, in some cases it can be difficult to decide whether the original baptism was valid, so if there is any doubt, a conditional baptism is employed, in which the officiant says something of the form of "if you are not yet baptized, I baptize you..." The need for conditional baptisms is motivated not only by factual uncertainties regarding the original baptism, but also by the uncertainty of some of the baptismal theology regarding the precise conditions for the validity of baptism. (The Church holds that one cannot be certain that opinions which are offered by pious theologians, but on which the Church has not made an authoritative pronouncement, are correct, and even authoritative pronouncements can have multiple interpretations which the Church has neither definitively endorsed or rejected.)

Jewish Background

The ritual of baptism is prefigured in the purification rites of Jewish law and tradition. In the Tanakh and tradition of the teachers of the Torah, a ritual bath for purification from uncleanness used to be required under specified circumstances in order to be restored to a condition of ritual purity. For example, women after menses, and after a number of blood-free days following child-birth, were washed in a ritual bath, called a mikvah. Those who became ritually defiled by contact with something infectious, would also use the mikveh as part of their healing. Washing was also required for converts. Through practices such as these, immersion in the mikveh came to represent purification and restoration, and qualification for full religious participation in the life of the community (Book of Numbers Chapter 19). Traditional conversion to Judaism also requires a mikvah, so for converts Jewish initiation is in some ways similar to Christian initiation, although the term baptism is not used to describe the Jewish conversion.

Baptism in the Gospels

St. John the Forerunner

A preliminary understanding of baptism starts with St. John the Forerunner, the cousin of Jesus. John spoke of a baptism of repentance in preparation for the coming of the Messiah.

"And he came into all the country about Jordan, preaching the baptism of repentance for the remission of sins; As it is written in the book of the words of Esaias the prophet, saying, The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight. Every valley shall be filled, and every mountain and hill shall be brought low; and the crooked shall be made straight, and the rough ways shall be made smooth; And all flesh shall see the salvation of God." (Luke 3:3-6 KJV, also see Matthew 3:1-6, Mark 1:1-5)

In regards to his relationship to the coming Messiah, John also spoke of another kind of baptism.

"John answered, saying unto them all, I indeed baptize you with water; but one mightier than I cometh, the latchet of whose shoes I am not worthy to unloose: he shall baptize you with the Holy Ghost and with fire: Whose fan is in his hand, and he will throughly purge his floor, and will gather the wheat into his garner; but the chaff he will burn with fire unquenchable." (Luke 3:16-17 KJV, also see Matthew 3:7-12, Mark 1:6-8)

Baptism of Christ

During John's earthly ministry Jesus came to receive baptism from John:

"And John bare record, saying, I saw the Spirit descending from heaven like a dove, and it abode upon him. And I knew him not: but he that sent me to baptize with water, the same said unto me, Upon whom thou shalt see the Spirit descending, and remaining on him, the same is he which baptizeth with the Holy Ghost. And I saw, and bare record that this is the Son of God." (John 1:32-34 KJV, also see Matthew 3:13-17, Mark 1:9-11)

There also seems to be some reference to Jesus and/or his disciples baptizing individuals, before His death on the cross (see John 3:22-26, John 4:1-3).

The Great Commission

After His resurrection, Jesus appeared to the disciples and spoke to them saying,

"...All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen." (Matthew 28:18-20 KJV, also see Mark 16:14-20, Acts 2:38)

The commandment of the Lord to baptize "in the name of the Father, and of the Son, and of the Holy Ghost" was the practice of the early church and is still the practiced method for baptizing today, although other methods exist (see Acts 2:38; 8:16; 10:48; 19:5).

"...Concerning the water, indeed, it is written, in reference to the Israelites, that they should not receive that baptism which leads to the remission of sins, but should procure another for themselves..." (The Epistle of Barnabas, Chapter 11, Roberts-Donaldson)

"Blessed are they who, placing their trust in the cross, have gone down into the water...we indeed descend into the water full of sins and defilement, but come up, bearing fruit in our heart, having the fear [of God] and trust in Jesus in our spirit." (The Epistle of Barnabas, Chapter 11, Roberts-Donaldson)

Martin Luther placed a great importance on baptism. Luther states in The Large Catechism of 1529 AD,

"To put it most simply, the power, effect, benefit, fruit, and purpose of Baptism is to save. No one is baptized in order to become a prince, but as the words say, to 'be saved.' To be saved, we know, is nothing else than to be delivered from sin, death, and the devil and to enter into the kingdom of Christ and live with him forever."